Method for detecting oxygen-containing functional groups in porous graphite phase in blast furnace pig iron

Abstract

This invention relates to the field of materials testing technology, and more particularly to a method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron. By using high-temperature argon-protected heating combined with rapid cooling pretreatment with ice-salt water, the precipitation of ordinary graphite phase is kinetically suppressed while preserving the porous graphite structure. Pure graphite particles are obtained through digestion with concentrated hydrochloric acid, filtration, washing, and drying. Trace amounts of graphite powder are mixed with spectrally pure KBr powder in a specific ratio and pressed into tablets. Vibrational behavior is detected using Fourier transform infrared spectroscopy to determine the type of oxygen-containing functional groups. This invention enables efficient and non-destructive extraction of the porous graphite phase from blast furnace pig iron and direct detection of its oxygen-containing functional groups. The experimental process is safe, accurate, and efficient, providing characterization technology support for the microscopic migration mechanism of rare earth elements in blast furnace ironmaking.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to a method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron. Background Technology

[0002] In the blast furnace smelting process of associated pig iron ores such as Bayan Obo, trace rare earth elements are reduced and adsorbed by oxygen-containing functional groups on the porous graphite in the molten iron, thus remaining in the blast furnace and entering the subsequent converter steelmaking process. Accurately detecting the type of oxygen-containing functional groups on the porous graphite phase in blast furnace pig iron is a key characterization technique for studying the microscopic migration mechanism of rare earth elements during blast furnace ironmaking. However, as blast furnace pig iron samples taken from the industrial site solidify and cool, the supersaturated carbon atoms inside form a large amount of ordinary graphite phase, severely interfering with the characterization and detection of the porous graphite phase. This makes it impossible for current techniques to directly identify oxygen-containing functional groups on the porous graphite phase from pig iron.

[0003] Existing detection methods mainly face the following shortcomings: First, traditional Fourier transform infrared spectroscopy is only applicable to pure carbon material powders and lacks a pretreatment method for efficiently and non-destructively separating porous graphite phases from blast furnace pig iron matrix; Second, although simple acid dissolution can remove the iron matrix, it cannot suppress the precipitation interference of ordinary graphite phases, and long-term high-temperature acid washing will destroy the oxygen-containing functional groups on the surface of the graphite phase; Third, in conventional KBr pellet preparation, the ratio of graphite to KBr is usually around 1:100. For trace porous graphite phases, the infrared absorption peak of graphite is too strong at this ratio, which will mask the weak signal of oxygen-containing functional groups and make it difficult to obtain clear functional group characteristic peaks.

[0004] Chinese Patent Publication No. CN109682846A discloses a comprehensive method for detecting carbon materials, using Fourier transform infrared spectroscopy to detect oxygen-containing functional groups in pure carbon materials such as graphene oxide. However, this method detects pure carbon material powder prepared in the laboratory and does not involve a pretreatment step for extracting porous graphite phases from blast furnace pig iron, thus failing to solve the problem of interference from ordinary graphite phases. Chinese Patent Publication No. CN109678148A discloses a method for purifying graphite in waste slag from synthetic diamond production, using concentrated hydrochloric acid digestion to purify graphite. However, its technical purpose is to recover high-purity graphite, rather than retaining the porous graphite structure for functional group detection, and its prolonged high-temperature acid washing will destroy the surface oxygen-containing functional groups. Therefore, existing technologies lack a method that can effectively extract porous graphite phases from blast furnace pig iron samples and accurately detect their oxygen-containing functional group types, making it difficult to meet the characterization needs for studying the microscopic behavior of rare earth elements in blast furnace ironmaking. Summary of the Invention

[0005] To address these issues, this invention provides a method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron. This method overcomes the limitations of existing technologies when analyzing the oxygen-containing functional group types in porous graphite phases of blast furnace pig iron samples during on-site steel production. These limitations include: the large-scale precipitation of ordinary graphite phase after cooling and solidification of blast furnace pig iron interferes with the characterization of the porous graphite phase; the lack of efficient and non-destructive pretreatment methods for extracting the porous graphite phase from the iron matrix; the limitation that traditional FTIR detection is only applicable to pure carbon powder and cannot directly detect pig iron samples; the masking of functional group signals due to improper graphite-to-KBr ratio in conventional KBr pellet preparation; and the inaccurate identification of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron due to prolonged high-temperature treatment in existing acid washing purification methods. These problems hinder the study of the microscopic migration mechanism of rare earth elements during blast furnace ironmaking.

[0006] To achieve the above objectives, this invention provides a method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron, comprising: Pig iron samples taken from the blast furnace ironmaking production site are placed in a graphite crucible and heated in a tube furnace filled with argon to a predetermined heating temperature range and held at that temperature for a predetermined holding time. The pig iron samples are then transferred to ice-salt water to cool to a predetermined cooling temperature range. The cooled pig iron sample was crushed into granules and placed in a conical flask containing concentrated hydrochloric acid, and digested into a digestion solution in a water bath within a predetermined digestion temperature range. The digestion solution is filtered, and the filtered residue is transferred to a drying oven in a predetermined first drying temperature range to dry into dry graphite particles. The dried graphite particles are transferred to a mortar and ground into powder, and the ground graphite powder is then screened through a first sieve. Weigh a first predetermined weight of spectrally pure KBr particles, place them in a mortar and grind them into powder, and then sieve the ground KBr powder through a second sample sieve. The ground KBr powder is placed in a drying oven at a predetermined second drying temperature and dried for a predetermined drying time; Weigh a second predetermined weight of the graphite powder and the KBr powder, put them into a mortar, mix them evenly, and grind them for a predetermined grinding time to obtain a mixed powder; The mixed powder is loaded into a tableting mold and pressed into a disc shape using a tableting machine. The vibrational behavior of the Fourier transform infrared spectrum in the disc sample is detected by a Fourier transform infrared spectrometer to obtain the type of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron.

[0007] Furthermore, before heating, the tube furnace filled with argon gas should be supplied with argon gas of ≥99.99% purity through the bottom gas pipe interface and flow out through the top gas pipe interface into a container filled with water to ensure that the furnace tubes are filled with argon gas and prevent air from entering during the heating and heat preservation process.

[0008] Furthermore, the ice-salt water is a saturated aqueous solution of NaCl, KCl, or a mixture of both, and is frozen to an ice-water mixed state.

[0009] Furthermore, during the digestion of the pig iron particles in concentrated hydrochloric acid, deionized water needs to be added intermittently to the conical flask to prevent the solution in the flask from evaporating to dryness.

[0010] Furthermore, the solution filtration process employs an organic filter membrane in a sand core filter or a slow-speed quantitative filter paper in a Buchner funnel for accelerated filtration under vacuum. After the first filtration, 10 mL to 15 mL of deionized water is added to the solution after the first filtration to rinse the filter residue 3 to 5 times, and then 5 mL to 15 mL of anhydrous ethanol is added to rinse the filter residue 2 to 4 times to obtain the filtered solution.

[0011] Furthermore, the first sampling sieve has a mesh size of 200 to 400 mesh and a sieve aperture of 38 μm to 74 μm.

[0012] Furthermore, the second sampling sieve has a mesh size of 1600 to 5000 mesh and a sieve aperture of 3 μm to 10 μm.

[0013] Furthermore, when storing the dried KBr powder, it needs to be placed in a desiccator containing silica gel particles or calcium oxide desiccant.

[0014] Furthermore, the compressive stress of the tablet press is set at 6000 kPa / cm² to 10000 kPa / cm², and the compressive stress holding time is 10 s to 60 s.

[0015] Further, the predetermined heating temperature range is 1150℃~1300℃; the predetermined holding time is 0.5h~2h; the predetermined cooling temperature range is 20℃~25℃; the predetermined digestion temperature range is 50℃~80℃; the predetermined first drying temperature range is 50℃~80℃; the first predetermined weight is 200mg~350mg; the predetermined second drying temperature range is 40℃~60℃; the predetermined drying time is 5min~10min; the second predetermined weight is 0.15mg~3mg; and the predetermined grinding time is 1min~3min.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By employing a pretreatment process combining high-temperature argon-protected heating with rapid cooling in ice-salt water, this invention effectively suppresses the excessive precipitation of ordinary graphite phases during the cooling and solidification of blast furnace pig iron, selectively preserving the original structure of the porous graphite phase. This solves the problem of ordinary graphite phases interfering with the characterization and detection of porous graphite phases in existing technologies. Furthermore, through concentrated hydrochloric acid digestion and multi-step filtration, washing, and drying processes, the porous graphite phase can be efficiently and non-destructively extracted from the iron matrix, yielding pure, dry, and structurally intact graphite particles. This overcomes the limitation that traditional FTIR detection is only suitable for pure carbon material powders. The limitations of directly detecting porous graphite phase samples in pig iron can be overcome by grinding and sieving the extracted graphite particles, grinding them separately with spectroscopically pure KBr to ultrafine and drying them, and mixing trace amounts of graphite powder and KBr powder in a very low ratio and pressing them into tablets. This effectively avoids the masking of functional group signals by the excessive infrared absorption of graphite itself, and significantly improves the signal-to-noise ratio of the characteristic peaks of oxygen-containing functional groups. By detecting the vibrational behavior of the disc-shaped samples using Fourier transform infrared spectroscopy, the types of oxygen-containing functional groups in the porous graphite phase can be accurately identified, providing key characterization technology support for studying the microscopic migration mechanism of rare earth elements in the blast furnace ironmaking process.

[0017] Furthermore, by holding the blast furnace pig iron sample at a high temperature of 1150℃~1300℃ under argon protection for 0.5h~2h, the graphite phase that should have cooled and crystallized or precipitated in the pig iron was re-dissolved, allowing the target porous graphite phase to be preserved separately. Subsequently, it was rapidly transferred to ice-salt water and quenched to 20℃~25℃, which kinetically suppressed the large-scale precipitation of ordinary graphite phase and achieved selective retention of porous graphite phase, creating the preconditions for subsequent extraction.

[0018] Furthermore, by crushing the cooled pig iron sample into granules and digesting it in concentrated hydrochloric acid at 50℃~80℃, the iron matrix is ​​dissolved while the graphite phase is almost undamaged. Then, it is vacuum filtered through an organic filter membrane or slow quantitative filter paper, and rinsed with deionized water 3~5 times and anhydrous ethanol 2~4 times in succession. This effectively removes metal ions, acid radicals and moisture, and obtains pure and dry graphite particles, thus achieving non-destructive extraction of the porous graphite phase in blast furnace pig iron.

[0019] Furthermore, by grinding the dried graphite particles and screening them through a 200-400 mesh sieve, and grinding the spectrally pure KBr particles and screening them through a 1600-5000 mesh sieve and then drying them, the particle size matching and uniform mixing of the graphite powder and KBr powder were ensured. By mixing and grinding 0.15mg-3mg of graphite powder and 200mg-350mg of KBr powder in an agate mortar for 1min-3min, the graphite was highly dispersed in the KBr matrix, effectively avoiding the signal inhomogeneity and excessively strong absorption peaks caused by graphite agglomeration.

[0020] Furthermore, by pressing the mixed powder into a disc shape under a compressive stress of 6000 kPa / cm² to 10000 kPa / cm² for 10 to 60 seconds, transparent, uniform, and consistent thickness disc samples were obtained, ensuring the repeatability and accuracy of infrared spectroscopy testing. By detecting the vibration behavior of the disc sample using a Fourier transform infrared spectrometer, the characteristic absorption peaks of oxygen-containing functional groups in the porous graphite phase could be clearly distinguished, achieving accurate detection of the type of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of a method for detecting oxygen-containing functional groups in porous graphite phases in blast furnace pig iron according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the steps involved in pretreating pig iron samples according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating the steps of digestion, filtration, and drying of the pig iron sample in an embodiment of the present invention. Figure 4 This is a flowchart illustrating the steps for obtaining the final sample in an embodiment of the present invention. Figure 5 This is a microscopic morphology diagram of porous graphite in pig iron from a blast furnace according to Embodiment 1 of the present invention. Figure 6 This is the Fourier transform spectrum of porous graphite in pig iron from a blast furnace according to Embodiment 1 of the present invention; Figure 7 This is a microscopic morphology diagram of porous graphite in pig iron from a blast furnace, as shown in Embodiment 2 of the present invention. Figure 8 This is the Fourier transform spectrum of porous graphite in pig iron from a blast furnace according to Embodiment 2 of the present invention. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] Please see Figure 1 The diagram shown is a flowchart illustrating a method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to an embodiment of the present invention. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to an embodiment of the present invention includes: S1: The pig iron sample taken from the blast furnace ironmaking production site is placed in a graphite crucible and heated in a tube furnace filled with argon to a predetermined heating temperature range and held at that temperature for a predetermined holding time. Then, the pig iron sample is transferred to ice-salt water to cool to a predetermined cooling temperature range. S2: The cooled pig iron sample is crushed into granules and placed in a conical flask containing concentrated hydrochloric acid, and digested into a digestion solution in a water bath within a predetermined digestion temperature range. S3: Filter the digestion solution and transfer the filtered residue to a drying oven in a predetermined first drying temperature range to dry it into dry graphite particles. S4: Transfer the dried graphite particles to a mortar and grind them into powder, and then screen the ground graphite powder through a first sieve. S5: Weigh the first predetermined weight of spectrally pure KBr particles, put them into a mortar and grind them into powder, and then pass the ground KBr powder through the second sample sieve. S6: Place the ground KBr powder into a drying oven at a predetermined second drying temperature and dry it for a predetermined drying time; S7: Weigh a second predetermined weight of the graphite powder and the KBr powder, put them into a mortar, mix them evenly, and grind them for a predetermined grinding time to obtain a mixed powder; S8: The mixed powder is loaded into a tableting mold and the mixed powder in the mold is pressed into a disc shape using a tableting machine. The vibration behavior of the Fourier transform infrared spectrum in the disc sample is detected by a Fourier transform infrared spectrometer to obtain the type of oxygen-containing functional groups in the porous graphite phase in blast furnace pig iron.

[0025] Specifically, the predetermined heating temperature range is 1150℃~1300℃; the predetermined holding time is 0.5h~2h; the predetermined cooling temperature range is 20℃~25℃; the predetermined digestion temperature range is 50℃~80℃; the predetermined first drying temperature range is 50℃~80℃; the predetermined first weight is 200mg~350mg; the predetermined second drying temperature range is 40℃~60℃; the predetermined drying time is 5min~10min; the predetermined second weight is 0.15mg~3mg; and the predetermined grinding time is 1min~3min.

[0026] Specifically, in Embodiment 1 of the present invention, the predetermined heating temperature is preferably 1230 ℃; the predetermined holding time is preferably 1 h; the predetermined cooling temperature is preferably 20 ℃ to 25 ℃; the predetermined digestion temperature is preferably 65 ℃; the predetermined first drying temperature is preferably 60 ℃; the first predetermined weight is preferably 300 mg; the predetermined second drying temperature is preferably 50 ℃; the predetermined drying time is preferably 7 min; the second predetermined weight is preferably 0.25 mg; and the predetermined grinding time is preferably 3 min.

[0027] Specifically, in Embodiment 2 of the present invention, the predetermined heating temperature is preferably 1250 ℃; the predetermined holding time is preferably 0.6 h; the predetermined cooling temperature is preferably 20 ℃ to 25 ℃; the predetermined digestion temperature is preferably 70 ℃; the predetermined first drying temperature is preferably 70 ℃; the first predetermined weight is preferably 220 mg; the predetermined second drying temperature is preferably 55 ℃; the predetermined drying time is preferably 6 min; the second predetermined weight is preferably 0.23 mg; and the predetermined grinding time is preferably 1.5 min.

[0028] This invention, through heating and holding the blast furnace pig iron sample under high-temperature argon protection before rapidly cooling it in ice-salt water, effectively suppresses the interference of excessive precipitation of ordinary graphite phase while selectively retaining the original structure of the porous graphite phase, thus improving the accuracy of subsequent extraction and detection. By crushing the rapidly cooled pig iron sample into particles and digesting it in concentrated hydrochloric acid, the iron matrix is ​​fully dissolved while the porous graphite phase is almost undamaged, improving the non-destructive nature and purity of graphite phase extraction. Vacuum filtration using an organic filter membrane followed by rinsing the filter residue with deionized water and anhydrous ethanol effectively removes metal ions, acid radicals, and moisture, improving the purity and structural integrity of the dried graphite particles. Grinding the dried graphite particles and screening them through a first sieve, while simultaneously grinding spectrally pure KBr particles and screening them through a second sieve before drying, ensures the particle size distribution of both graphite and KBr powders. Matching and uniform dispersion improve the reliability of subsequent pelleting and spectral detection. By weighing and mixing graphite powder with KBr powder in an agate mortar and grinding them, graphite can be highly dispersed in the KBr matrix, avoiding the masking of oxygen-containing functional group signals by excessive infrared absorption of graphite itself, and improving the signal-to-noise ratio of characteristic peaks of oxygen-containing functional groups. By pressing the mixed powder into discs under compressive stress, transparent, uniform, and consistent thickness pellets can be obtained, improving the repeatability and accuracy of Fourier transform infrared spectroscopy. By detecting the vibrational behavior of disc-shaped samples using Fourier transform infrared spectroscopy, the types of oxygen-containing functional groups in porous graphite phases can be accurately identified, realizing the direct detection of oxygen-containing functional groups in porous graphite phases in blast furnace pig iron. With clear parameters and controllable operation in each step of the entire detection process, and without involving dangerous high-temperature and high-pressure operations, the experimental process is safe and the analysis and detection are accurate and efficient.

[0029] Please see Figure 2 The diagram shown is a flowchart illustrating the steps of pretreating pig iron samples according to an embodiment of the present invention. The process of pretreating pig iron samples according to an embodiment of the present invention includes: Place the pig iron sample into a graphite crucible; The graphite crucible is heated to a predetermined heating range in a tube furnace protected by high-purity argon gas and held at that temperature for a predetermined time. The treated pig iron sample was transferred to ice-salt water and cooled to 20℃~25℃. Pretreated pig iron samples were obtained.

[0030] Specifically, before heating, the tube furnace filled with argon gas should be filled with argon gas of ≥99.99% purity through the bottom gas pipe interface and flow out through the top gas pipe interface into a container filled with water to ensure that the furnace tubes are filled with argon gas and prevent air from entering during the heating and heat preservation process.

[0031] Specifically, the ice-salt water is a saturated aqueous solution of NaCl, KCl, or a mixture of both, and is frozen to an ice-water mixture state.

[0032] Specifically, in Embodiment 1 of the present invention, the ice-salt water is a saturated NaCl aqueous solution that has been frozen to a mixed ice-water state.

[0033] Specifically, in Embodiment 2 of the present invention, the ice-salt water is a saturated NaCl and KCl aqueous solution with a mass ratio of 2:1, which is then frozen to a mixed ice-water state.

[0034] This invention, through heating and holding a pig iron sample under high-purity argon protection, enables the reappearance and stable existence of the target porous graphite phase. By introducing high-purity argon gas at the bottom and preventing air from entering, high-temperature oxidation of the pig iron sample and its graphite phase is avoided. By rapidly transferring the sample to ice-salt water and quenching it to 20°C–25°C, the rapid cooling kinetically suppresses interference from the precipitation of ordinary graphite phase, achieving selective retention of the porous graphite phase and providing high-quality samples for detection.

[0035] Please see Figure 3 The diagram shows a flowchart of the digestion, filtration, and drying steps of the pig iron sample according to an embodiment of the present invention. The process of digestion, filtration, and drying of the pig iron sample according to an embodiment of the present invention includes: The pretreated pig iron sample was crushed into granules. The granular pig iron sample was placed in a conical flask containing concentrated hydrochloric acid and digested in a water bath. The digestion solution was initially filtered using an organic filter membrane in a sand core filter. After rinsing the filter residue with deionized water a predetermined number of times, rinse the filter residue with anhydrous ethanol a predetermined number of times. Place the filtered residue into a drying oven and dry it. Dry graphite particles are obtained.

[0036] Specifically, the pretreated pig iron sample becomes brittle after rapid cooling and is broken into 4mm particles for easy acid dissolution.

[0037] Specifically, the concentrated hydrochloric acid has a mass fraction of 37%.

[0038] Specifically, deionized water needs to be added intermittently during the digestion process to prevent the liquid from evaporating to dryness. Add 8 mL of deionized water every 30 minutes.

[0039] Specifically, a 0.45μm organic filter membrane is used in a sand core filter for filtration to accelerate solid-liquid separation.

[0040] Specifically, in Embodiment 1 of the present invention, after the first filtration, the filter residue is rinsed three times with 10 mL of deionized water, and then rinsed three times with 10 mL of anhydrous ethanol to replace the water.

[0041] Specifically, in Embodiment 2 of the present invention, after the first filtration, the filter residue is rinsed 5 times with 10 mL of deionized water, and then rinsed 4 times with 5 mL of anhydrous ethanol to replace the water.

[0042] This invention improves digestion efficiency by crushing pretreated pig iron samples into granules, increasing the contact area with concentrated hydrochloric acid, accelerating the dissolution of the iron matrix, and enhancing digestion efficiency. Digestion in concentrated hydrochloric acid in a water bath until no metal residue remains ensures complete dissolution of the iron matrix while preserving the porous graphite phase, improving the non-destructive nature of graphite phase extraction. Intermittent addition of deionized water during digestion prevents incomplete digestion due to liquid evaporation, ensuring a continuous and stable digestion reaction. Using a 0.45μm organic filter membrane in a sand core filter enables rapid solid-liquid separation, improving filtration efficiency. Rinsing the filter residue with deionized water followed by anhydrous ethanol after the initial filtration effectively removes residual hydrochloric acid, metal ions, and moisture, improving the purity of the graphite particles. Drying the filter residue to constant weight in a drying oven removes moisture while avoiding high-temperature damage to oxygen-containing functional groups, resulting in pure, dry, and structurally intact graphite particles, providing high-quality graphite samples for grinding, tableting, and infrared spectroscopy.

[0043] Please see Figure 4 The diagram shown is a flowchart illustrating the steps for obtaining the final sample according to an embodiment of the present invention. The process for obtaining the final sample according to an embodiment of the present invention includes: Dry graphite particles are placed in a mortar and ground into graphite powder. The graphite powder was screened through the first sieve. Spectroscopically pure KBr particles were ground into KBr powder in a mortar; The KBr powder was screened through a second dividing sieve. The screened KBr powder was placed in a drying oven and dried. Weigh out the predetermined weights of the screened graphite powder and the treated KBr powder respectively. Graphite powder and KBr powder are mixed in a mortar and ground to obtain a mixed powder; The mixed powder is placed in a tablet press and pressed into round tablets.

[0044] Specifically, in Embodiment 1 of the present invention, the ground graphite powder is poured into a 200-mesh sieve, the sieve is gently vibrated, and the powder passing through the sieve is collected for later use; coarse particles that fail to pass through the sieve need to be ground and sieved again to ensure that the particle size of the graphite powder is less than 74μm.

[0045] Specifically, in Embodiment 2 of the present invention, the ground graphite powder is poured into a 400-mesh sieve, the sieve is gently vibrated, and the powder passing through the sieve is collected for later use; coarse particles that fail to pass through the sieve need to be ground and sieved again to ensure that the particle size of the graphite powder is less than 38μm.

[0046] Specifically, in Embodiment 1 of the present invention, the ground KBr powder is poured into a 1600-mesh sieve, vibrated and sieved, and the fine powder under the sieve is collected. Particles that do not pass through the sieve need to be ground until all of them pass through the sieve to ensure that the particle size of the KBr powder is less than 10μm.

[0047] Specifically, in Embodiment 2 of the present invention, the ground KBr powder is poured into a 5000-mesh sieve, vibrated and sieved, and the fine powder under the sieve is collected. Particles that do not pass through the sieve need to be ground until all of them pass through the sieve to ensure that the particle size of the KBr powder is less than 3μm.

[0048] Specifically, in Embodiment 1 of the present invention, the sieved KBr powder is evenly spread in a petri dish and dried in a 50°C constant temperature drying oven for 7 minutes.

[0049] Specifically, in Embodiment 2 of the present invention, the sieved KBr powder is evenly spread in a petri dish and dried in a 55°C constant temperature drying oven for 6 minutes.

[0050] Specifically, when storing dried KBr powder, it should be placed in a desiccator containing silica gel particles or calcium oxide desiccant.

[0051] Specifically, in Embodiment 1 of the present invention, a microbalance is used to accurately weigh 0.25 mg of sieved graphite powder and 300 mg of dried KBr powder. The weighing accuracy needs to reach 0.01 mg to ensure the accurate ratio of graphite to KBr.

[0052] Specifically, in Embodiment 2 of the present invention, a microbalance is used to accurately weigh 0.23 mg of sieved graphite powder and 220 mg of dried KBr powder. The weighing accuracy needs to reach 0.01 mg to ensure the accurate ratio of graphite to KBr.

[0053] Specifically, in Embodiment 1 of the present invention, the weighed graphite powder and KBr powder are placed together in a mortar and mixed and ground for 3 minutes to achieve a high degree of uniform dispersion of graphite powder in the KBr matrix.

[0054] Specifically, in Embodiment 2 of the present invention, the weighed graphite powder and KBr powder are placed together in a mortar and ground for 1.5 minutes to achieve a high degree of uniform dispersion of graphite powder in the KBr matrix.

[0055] Specifically, in Embodiment 1 of the present invention, the uniformly mixed powder is loaded into a matching tableting mold, placed on the worktable of a tablet press, and subjected to a compressive stress of 6500 kPa / cm² for 50 seconds to obtain a round tablet sample.

[0056] Specifically, in Embodiment 2 of the present invention, the uniformly mixed powder is loaded into a matching tableting mold, placed on the worktable of a tablet press, and subjected to a compressive stress of 8000 kPa / cm² for 13 seconds to obtain a round tablet sample.

[0057] Specifically, by using a Fourier transform infrared spectrometer to detect the vibrational behavior of the Fourier transform infrared spectrum in a disc-shaped sample, the type of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron can be obtained.

[0058] Please see Figure 5 As shown, it is a microscopic morphology diagram of porous graphite in pig iron from a blast furnace according to Embodiment 1 of the present invention.

[0059] Please see Figure 6 As shown, it is the Fourier transform spectrum of porous graphite in pig iron from a blast furnace according to Embodiment 1 of the present invention.

[0060] Please see Figure 7 As shown, it is a microscopic morphology diagram of porous graphite in blast furnace pig iron in Embodiment 2 of the present invention.

[0061] Please see Figure 8 As shown, it is the Fourier transform spectrum of porous graphite in blast furnace pig iron in Embodiment 2 of the present invention.

[0062] This invention, through grinding dried graphite particles and passing them through a first sampling sieve, obtains graphite powder with uniform particle size, improving the uniformity of subsequent mixing and dispersion. By grinding spectrally pure KBr particles, passing them through a second sampling sieve, drying them, and storing them in a desiccator containing a desiccant, the moisture adsorbed by the KBr is effectively removed, maintaining its dryness and preventing moisture absorption during tablet pressing that could reduce the transparency of the discs. By accurately weighing trace amounts of graphite powder and appropriate amounts of KBr powder using a microbalance and mixing and grinding them in a specific ratio, the graphite powder achieves high and uniform dispersion in the KBr matrix, avoiding the masking of oxygen-containing functional group signals by excessive infrared absorption of graphite itself. By forming the mixed powder into disc-shaped samples under compressive stress, transparent, uniform, and consistent thickness tablets are obtained, improving the repeatability and accuracy of Fourier transform infrared spectroscopy detection, thereby achieving reliable detection of the types of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron.

[0063] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications or substitutions should be covered within the scope of the claims of this application.

Claims

1. A method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron, characterized in that, include: Pig iron samples taken from the blast furnace ironmaking production site are placed in a graphite crucible and heated in a tube furnace filled with argon to a predetermined heating temperature range and held at that temperature for a predetermined holding time. The pig iron samples are then transferred to ice-salt water to cool to a predetermined cooling temperature range. The cooled pig iron sample was crushed into granules and placed in a conical flask containing concentrated hydrochloric acid, and digested into a digestion solution in a water bath within a predetermined digestion temperature range. The digestion solution is filtered, and the filtered residue is transferred to a drying oven in a predetermined first drying temperature range to dry into dry graphite particles. The dried graphite particles are transferred to a mortar and ground into powder, and the ground graphite powder is then screened through a first sieve. Weigh a first predetermined weight of spectrally pure KBr particles, place them in a mortar and grind them into powder, and then sieve the ground KBr powder through a second sample sieve. The ground KBr powder is placed in a drying oven at a predetermined second drying temperature and dried for a predetermined drying time; Weigh a second predetermined weight of the graphite powder and the KBr powder, put them into a mortar, mix them evenly, and grind them for a predetermined grinding time to obtain a mixed powder; The mixed powder is loaded into a tableting mold and pressed into a disc shape using a tableting machine. The vibrational behavior of the Fourier transform infrared spectrum in the disc sample is detected by a Fourier transform infrared spectrometer to obtain the type of oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron.

2. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, Before heating, the tubular furnace filled with argon gas should be supplied with argon gas of ≥99.99% purity through the bottom gas pipe interface and flow out through the top gas pipe interface into a container filled with water to ensure that the furnace tubes are filled with argon gas and to prevent air from entering during the heating and heat preservation process.

3. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The ice-salt water is a saturated aqueous solution of NaCl, KCl, or a mixture of both, and is frozen to an ice-water mixture state.

4. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, During the digestion of the pig iron particles in concentrated hydrochloric acid, deionized water needs to be added intermittently to the conical flask to prevent the solution in the flask from evaporating to dryness.

5. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The solution filtration process employs an organic filter membrane in a sand core filter or a slow-speed quantitative filter paper in a Buchner funnel for accelerated filtration under vacuum. After the first filtration, 10 mL to 15 mL of deionized water is added to the solution after the first filtration to rinse the filter residue 3 to 5 times. Then, 5 mL to 15 mL of anhydrous ethanol is added to rinse the filter residue 2 to 4 times to obtain the filtered solution.

6. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The first sampling sieve has a mesh size of 200 to 400 mesh and a sieve aperture of 38 μm to 74 μm.

7. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The second sampling sieve has a mesh size of 1600 to 5000 mesh and a sieve aperture of 3 μm to 10 μm.

8. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, When storing the dried KBr powder, it needs to be placed in a desiccator containing silica gel particles or calcium oxide desiccant.

9. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The compressive stress of the tablet press is set at 6000 kPa / cm² to 10000 kPa / cm², and the compressive stress holding time is 10 s to 60 s.

10. The method for detecting oxygen-containing functional groups in the porous graphite phase of blast furnace pig iron according to claim 1, characterized in that, The predetermined heating temperature range is 1150℃~1300℃; the predetermined holding time is 0.5h~2h; the predetermined cooling temperature range is 20℃~25℃; the predetermined digestion temperature range is 50℃~80℃; the predetermined first drying temperature range is 50℃~80℃; the predetermined first weight is 200mg~350mg; the predetermined second drying temperature range is 40℃~60℃; the predetermined drying time is 5min~10min; the predetermined second weight is 0.15mg~3mg; and the predetermined grinding time is 1min~3min.

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